Preparation of 4-alkyl halo-phenols



Patented July 27, 1937v UNITED STATES.

TENT OHQE 2,087,986 PREPARATION OF 4-ALKYL HALO-PHENOLS Lindley E.Mills, Midland, Mich, assignor to The Dow Chemical Company, Midland,Mich., a cornotation of Michigan No Drawing. Original'applicationsFebruary 3, 1933, Serial No. 655,086, and October 29, 1934, Serial No.750,598. Divided and this application June 27, 1936, Serial No. 87,763

2 Claims. (Cl. 260-454) I have prepared compounds of the aforemen tionedclass, determined certain physical proper ties'thereof whereby they maybe readily identi- ,fied,a'nd found that they have high phenolcoefficients and may advantageously be used for Variousv purposes, forexample as antiseptics and germicides. It is'thbbject of this inventionparticularly to provide a process for the preparation of these valuablenew compounds. The invention, then, consists of the process hereinafterfully described and particularly pointed out in the claims.

The preparation of these new compounds can be accomplished by treatingi-alkyl substituted phenol, containing more than 5 carbon atoms in thealkyl group, directly with a halogen, thereby to replace at least one ofthe hydrogen atoms with said halogen. For example, such a phenol isplaced in a closed reactor, preferably provided with an agitator, ahalogen inlet, and an outlet suitable for the removal of the hydrogenhalide gas formed during the course of the reaction. The phenol isheated above the melting point, usually between about 20 and about 0.,if the material is normally a solid, and halogen then introduced belowthe surface of the liquid. A solvent for the phenol, which is nothalogenated under the conditions of the reaction, may be used ifdesired. Among the solvents I have found suitable for use is carbontetrachloride. The halogen may be added to the reaction mixture in anyconvenient manner; for instance, if the halogen is chlorine it may bebubbled through the reaction mixture, while in the case of bromine itcan be dropped upon the surface or introduced below the surface of themixture. After the desired amount of halogen has been introduced intothe reactor, the reaction mixture is blown with air to insure removal ofany small amounts of hydrogen halide remaining therein. alkylhalo-phenol product can then be separated from the reaction product byfractional distillation, preferably in vacuo, or the product may simplybe allowed to cool, if the compound produced will crystallize from thesolution. When the halo-phenol produced is solid at room temperature,the use of a solvent permits the halogenation to be effected at lowtemperature. This in turn benefits the yield of the halo-phenol, sinceThe 4- at lower temperatures there is less formation of tar and otherundesirable products such as higher halogenated phenols.

The following examples illustrate in detail my process for thepreparation of i-alkyl substituted halo-phenols wherein the substitutingalkyl group contains more than 5 carbon atoms:

Example 1 .In a reactor provided with an agitator was placed 1'76 gramsof i-cyclohexyl-phenol. The phenol was melted by heating to atemperature of about 130 C., and grams of bromine was introduced slowlybelow the surface of the molten compound. The reaction mixture washeated to maintain it liquid throughout the bromination. After thereaction was completed the product was blown with air to remove a slightamount of hydrogen bromide remaining therein, and then fractionated invacuo. The first fraction, distilling over up to 163 C. at 10millimeters absolute mercury pressure, amounted to 9.5 grams.

The second fraction of 111.0 grams, boiling between 163 and 168 C. atthe same pressure, was substantially pure i-cyclohexyl-2-bromo-phenol.The third fraction, distilling above 168 C., amounted to 65.5 grams andwas found to contain considerable quantities ofl-cyclohexyl-Zfidibromo-phenol. The middle fraction of4-cyclohexyl-Z-bromo-phenol was re-fractionated .at 3 millimetersabsolute mercury pressure, and pure 4-cyelohexyl-2-bromo-phenol boilingat 130-432 C. under 3 millimeters absolute pressure was obtained. Thecompound is a colorless viscous liquid havinga specific gravity of 1.356compared to water at 15 C., and having a phenol coefficient of 5.5. The4-cyclohexyl-2,6-dibromophenol separated from the third fraction had aspecific gravity of 1.667 at 15/ 15 C., and a boillined, using chlorineas a halogenating agent,

has a boiling point of 165 C. at 2 millimeters and a freezing point of53 C.

Example 2 I have treated 200 grams (0.97 mol.) of 4-tertiary octylphenol with chlorine at a temperature of 80-110 C, until 0.97 mol. ofhydrogen chloride was evolved. The reaction product was thenfractionally distilled and 181.5 grams of 2-chloro- Jr-tertiary cctylphenol, a 78 per cent of theoretical yield, was recovered. The boilingpoint of the compound is l4 5-l50 C. at 5-6 millimeters of mercurypressure absolute. The specific gravity at 25 C./25 C. is 1.055.Analysis of the compound for chlorine gave 15.01 per cent of halogenwhich is very close to the theoretical percentage 15.00. The phenolcoefficient of the compound is 8.0.

Example 3 In the preparation of this compound I treated 348 grams (1.22mols) of 2-bromo-4-tertiary octyl phenol, at a temperature of 80-100 C.,with 195 grams (1.22 mols) of bromine. The yield of dibromo-compound was324.5 grams or '73 per cent of theoretical. The boiling point of thiscompound is 158-163 C. at 3-6 millimeters of mercury pressure absolute.The specific gravity of the material is 1.455 at 25 0/25" C. Analysisfor percentage of bromine showed 44.29 per cent present as compared witha theoretical percentage of 44.00. The phenol coefiicient of thecompound is 8.0.

The above-described process is also applicable in the preparation of thehalogen derivatives of the l-alkyl phenols having more than 5 carbonatoms in the substituting alkyl group, wherein the alkyl group is anormal or secondary group.

The phenol coefficients given for the above compounds were determinedagainst E. typhi by the method developed by the United States PublicHealth Service Hygienic Laboratory, as described in Circular Number 198of the Food and Drug Administration, United States Department ofAgriculture.

This application is a division of my prior applications Serial Number655,086, filed 3 February 1933; and Serial Number 750,598, filed 29October 1934.

Other modes of applying the principle of my invention may be employedinstead of those explained, change being made as regards the materialsemployed, provided the step or steps recited in the'following claims becarried out.

I therefore particularly point out and distinctly claim as my invention:

1. The process of producing compounds having high phenol coefficientscomprising the treatment of a 4-alkyl phenol, having more than fivecarbon atoms in the alkyl group, with a reagent capable of introducing ahalogen substituent in place of one of the hydrogen atoms.

2. The process of producing compounds having high phenol coefiicientscomprising the treatment of a l-alkyl phenol, having more than fivecarbon atoms in the alkyl group, with a reagent capable of replacing oneof the hydrogen atoms of the benzene ring by a halogen substituent.

LIN'DLEY E. MILLS.

